The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Generally, typical power control installations require selection of the discrete components, customized mounting and wiring for each component and feature, and numerous connections. Additionally, any changes, additions, modifications, and replacements require disconnection and reconnection of various wire leads, yet again increasing the opportunity for wiring mistakes. As such, existing power control installations are often complex and costly to install. Such complexity and costs also limits their application or often limits the functionality included in a particular user application. For example, a limit control, over-voltage, or power monitoring component or functionality may not be included in some user applications when not required by a regulation due to the incremental complexity and cost.
One example of such a power control installation is a control system application for controlling the power provided to a power-receiving load where the power receiving load is a heater supplying heat to a temperature controlled manufacturing process. Incumbent installed process heaters can include a thermal fuse that opens the power connection to the heater under excessive temperature operating conditions, thereby protecting the heater system and the process it heats. However, it is known that a thermal fuse can fail prematurely due to environmental degradation of the fuse material over time and thermal fuse exposure to high temperature process transients (e.g., high temperature exhaust gases in a semiconductor manufacturing process) temporarily exposing the fuse to temperatures above the device's ratings causing the fuse to open, rendering the heater useless. Additionally, the premature failure of relay contacts, used as power switching devices, can also occur.
In such instances, the production system is halted and the affected heater components must be replaced by operating system maintenance personnel or the heater system vendor. Costly downtime and loss in process yields can result from such premature component failures. It is desirable to eliminate components that can succumb to premature environmental failures.
Incumbent heating systems may also be characterized by a requirement to shut them down to replace or recalibrate sensor components specific to a given process. For example, if a production process is capable of producing multiple products, with each process environment having a different range of operating temperature limits (e.g., differing mixes of constituent process gases), it may be necessary to shut down the system operation to reset the heater sensor parameters or replace standard sensor parts within the heater system to accommodate the change in production requirements. Existing systems do not provide any flexibility associated with production changes to thermal heating control systems without disabling heater and production system operation.
Existing systems often also have limited in-operation re-programmability and do not provide for convenient user changing of a set point temperature in a thermal application during operation and conveniently for the user. These systems must be built from a variety of discrete components and mounted at various positions within a cabinet or operational environment, some of which offer low circulation, high heat and other hostile environmental conditions.
The aforementioned limitations of the existing power and thermal control systems are recognized by the inventors hereof and some or all of these limitations have been addressed by various embodiments of the current invention.